3io BOTANICAL GAZETTE Ioctobkr 



Method 



By opening the stopcock E and F, mercury was allowed to flow 

 from the leveling burette into the cylinder until the latter was 

 about two-thirds full. A plug of the tissue from which the gas 

 was to be extracted was then cut with a cork borer. By using a 

 sharp borer and cutting clean, the epidermal layers sealed each 

 end of the plug of tissue, while all cut surfaces were in close con- 

 tact with the walls of the cork borer. Consequently, there was no 

 opportunity for contamination of the sample with the air. 



The tip of the cork borer was then put under the mercury in the 

 cylinder, and the sample plug of tissue pushed out under the mer- 

 cury; a long glass rod has been found satisfactory for this. The 

 plug was held beneath the mercury while the rod was replaced by 

 a wire spring, and the ground glass stopper fitted into the cylinder. 

 A mercury seal above the stopper precluded the possibility of leaks. 

 The stopcocks (E and F) were again opened, and all air in the cylinder 

 and capillary tubing replaced by mercury. The tip of the capillary 

 was immersed under mercury in D, the cock (E) closed, and the 

 leveling burette (A) lowered. The partial or almost complete 

 vacuum in the cylinder causes the gas in the tissue to expand; it 

 escapes from the tissue and collects in the top of the cylinder. The 

 first few bubbles of gas were always discarded by driving them 

 out through the capillary. When sufficient gas for the final 

 analysis had collected in the top of the cylinder, it was driven off 

 and collected over mercury in a small vial. The sample was 

 transferred to a Bonnier-Mangin gas analysis apparatus of the 

 type described originally by Aubert (2) and later by Grafe (4). 

 C0 2 absorption was by means of 15 per cent KOH; oxygen was 

 absorbed by 8 per cent pyrogallic acid in 30 per cent KOH. About 

 one-half cc. of gas is sufficient for an analysis in this apparatus. 



Results 



Three boxes of Yellow Newton apples, representing three differ- 

 ent trees at Watsonville, California, were used in the analyses 

 of gas in apples. Some apples from each box were stored in a 

 refrigerator at 6° C. and at n° C. Others were stored in a vessel 

 immersed in a water bath held at 20 C; while a fourth lot was 



